Charles a



(No Model.) I

' G. A. TERRY.

GORE FOR ELECTRICAL APPARATUS; No. 434,164. Patented Aug. 12, 1890.

' Fig.1. Fi .2.

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wbbmow gmvam UNITED Y STATES PATENT 1 OFFICE.

CHARLES A. TERRY, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO THE WVESTINGHOUSE ELECTRIC COMPANY, OF SAME PLACE.

CORE FOR ELECTRICAL APPARATUS.

SPECIFICATION forming part of Letters Patent No. 434,164, dated. August 12, 1890.

Application filed June 28,1889. $erial No. 315,930- (No model.)

To all whom it may concern.-

Be it known that I, CHARLES A. TERRY, a citizen of the United States, residing in Pittsburg, county of Allegheny, and State of Pennsylvania, have invented a certain new and useful Improvement in Cores for Electrical Apparatus, (Case No. 338,) of which the following is a specification.

The invention relates to the construction of cores and core-plates for electrical apparatus, and especially to those employed in building converters.

It has been found in practice that the cores of electrical apparatus, which are subject to rapid changes of magnetic condition, are more efficient and less liable to become heated when built up of insulated laminae of magnetizable material than when made solid. This is due to the fact that electric currents are generated in solid cores and render the apparatus less efficient. Such currents, while of comparativcl y low electro-motive force, are of considerable quantity. By laminatingthe cores and insulating the laminze, such currents are prevented from circulating. The use of laminated cores has therefore become quite uni-- versal. Different ways have been adopted for insulating the laminae from each other. It has been proposed to anneal the plates forming the laminze after they have been stamped into the proper shape, and rely upon the oxide of the metal formed by the annealing process to prevent the circulation of such currents. The advantage of annealing the plates after they have been stamped lies in the fact that it reduces the burrs and rough edges which are formed by the stamping process and which would tend to destroy the insulation to a greater or less extent if the annealingwere done before the plates were stamped. At the same time it softens the plates and covers the surfaces and edges with an oxide possible; but in order to permit the plates to be applied to the coils the iron through which the magnetic circuit is completed is cut apart. The confronting edges of these cuts come opposite to each other when the plates are in position, and form a more or less perfect contact; but it is evident that if the plates be thus out before they are annealed these edges will become more or less coated with the oxide, which may tend to render the magnetic 6o circuits more or less imperfect.

The object of the present invention is to insure that the magnetic circuit through the individual plates shall not be thus impaired; and it consists, in general terms, in providing plates which shall be insulated with the exception of the confronting edges through which the magnetic circuits are to be completed. This may be accomplished by forming the plates, with the exception of the opening or openings which are to be out through the magnetic circuit, then annealing, and afterward cutting the plate at such point or points as may be necessary or convenient for allowing them to be applied to the coils. The 7 5 burrs formed upon the edges of the cut through the magnetic circuit are not suflicient to appreciably impair the efficiency of the converter by allowing the circulation of Foucault currents.

It may in some instances be desired to stamp the plates and form the cut or cuts referred to before annealing or insulating and then remove the oxide or insulation from these edges; but usually this is not as convenient as the first method.

In the accompanying drawings there is shown in Figure l a converter-plate stamped with openings for receiving the coils and in a condition to be annealed, and Fig. 2 shows the plate after it has been annealed and the cut applied thereto for permitting it to be applied to the coils. Fig. 3 is an elevation of the converter with the core-plates applied.

Referring to the figures, A represents the body of the converter-plate, of a convenient form. It is constructed with two rectangular openings 6 c These openings may with advantage be formed' by stamping. After the plate has been stamped it is oxidized by any suitable process, preferably by an annealing process, which has the double advantage of oxidizing and softening the plate at the same time. The cuts f f (see Fig. 2) are then formed from the openings 6 e to the exterior of the plate, for allowing the plates to be applied to the converter-coils in the general manner described in Letters Patent No. 366,347, issued July 12, 1888. The plates are then applied to the coils B to form the core in the usual manner.

The invention is applicable to converters of other forms than that described, as it is evident that any converter-plate in which the magnetic circuit is cut open before the plates are applied to the coils may be treated in the same Way. Cores of other apparatus than converters may be made in the manner described.

In some instances it may be desired to stamp the openings or cuts f f before an nealing, and then remove the oxide which is formed at the confronting edges by means of attrition or in any other suitable manner.

I claim as my invention-- 1. A core-plate for electric converters, consisting of a sheet of soft iron having one or more openings formed therein forreceivingthe converter-coils, and having its edges and surfaces coated by oxide of iron, and having one or more cuts transverse to the magnetic circuit of the plate, the edges of such cuts being bare, substantially as described.

2. A core for electrical apparatus, composed of plates of magnetizable material having their surfaces and edges coated with an oxide, and having one or more cuts transverse to the magnetic circuits, the edges of said cuts being uninsulated.

3. A core for electrical apparatus, consisting of thin stamped plates of magnetizable material placed side by side, having cuts transverse to the magnetic circuit of the same, and intervening layers or laminre of electrical insulating oxide formed upon and covering the entire surfaces and edges of the plates with the exception of the edges of the said transverse cuts.

4. A core for electrical apparatus, consisting of annealed plates of magnetizable material placed side by side and having openings for receiving the coils of the apparatus, and having one or more cuts formed from such openings through the metal of the plates, and strata of insulating material upon the surfaces of the plates and covering the edges thereof with the exception of the edges formed by such cuts.

5. The hereinbefore-described method of forming the core-plates for electrical apparatus, consisting in first stamping the plates into the form required and then annealing, and afterward forming the openings through the plates for allowing them to be applied to the apparatus, substantially as described.

6. The hereinbefore-described method of forming core-plates for electrical apparatus, which consists in forming the plates, insulating their surfaces, and afterward cutting through the magnetic circuit thereof, substantially as described.

7. The hereinbefore-described method of building converters, which consists in forming the coils, forming core-plates to be applied thereto with continuous magnetic circuits, coating the plates with an oxide, cutting through the magnetic circuit, and applying the plates to the coils.

8. The hereinbeforc-described method of constructing cores for electrical apparatus, which consists in first stamping out the plates of magnetizable material, such as soft iron, afterward coating the edges of the same with an insulating oxide, forming one or more cuts transverse to the magnetic circuits of such plates, and building up the core from such oxidized plates after such cuts have been made.

In testimony whereof I have hereunto subscribed my name this 25th day of June, A. D.

CHARLES A. TERRY.

Witnesses:

W. D. UPTEGRAFF, J. W. SMITH. 

